Telephone system



J. A. HALL.

TELEPHONE SYSTEM.

APPLICATION man JULY 24.1917.

Patented Nov. 30, 1920.

3 SHEETS-SHEET I.

Jah/7 f4. Hal/A J. A. HALL.

l TELEPHONE SYSTEM. APPLicATroN FILED luLY 24.1911.

1,360,738. l Patented Nov. 30, 1920.

3 SHEETS-SHEET 2.

'by Ww@ J. A. HALL.

TELEPHONE SYSTEM.

1,860,738' I APPucmou msn :uw 24, 1917. atend NOV. 30 192.0.

3 SHEETS-SHEET 3.

CAD

UNITED STATES PATENT OFFICE.,

.TOEN A. HALL, OE EAST ORANGE, NEW JEizsEY, AssrGNOR To WEsTEEN ELECTRIC COMPANY, INCORPORATED, OE NEW YORK, N. Y., A 'COEPORATION'OE NEW YORK.

TELEPHONE SYSTEM.

specification of Leaerilsraien. Patented NOV, 30, 1920 Application filedJuly 24, 1917. *.Serial No. 182,465.

[o all whom t may concern.'

Be it known that I, JOHN A. HALL, a citizen of the United States, residing at East Orange, in the county of Essex and .State of New Jersey, have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systems of the type employing machine switching, and is related more particularly to means for establishing connections between subscribers substations in systems of great capacity.

The invention has for its object the provision of means for overcoming the psychological difficulty usually experienced in establishing connections inV automatic telephone systems of great capacity. Usually the decimal system of designating telephones is used, whence in systems exceeding One hundred thousand subscribers substatioiis, the proper manipulation of the dial switch in calling becomes psychologically diflicult, not to say impossible, when the fact that only a very few failures to get the right party in the totalnumber called makes the difference between a commercial success and a commercial failure, is considered. The object, then, is to provide means for operating a systemV of unlimited c apacity free from the objection thus attached to the Oidiiiary syst-em as it would be if its capacity were greatly increased.

Attempts vhave heretofore been made to increase the capacity of an automatic system and still avoid the difficulty mentioned. The means employed were in almost every Case far from the vstandard practice of the present day, and lso far fewhave proved commercial. As an instance, it has been proposed to increase the number of ways that each digital position of a telephone designation can be lilled, by using letters or othepr distinctive characters in addition to the usual ten digits. This scheme, however, contemplates the use of apparatus of largely vincreased capacity and quite different from that beingmanufactured at the present time. Another object of the invention, then, is to so arrange the present system that standard apparatus, dial switches, selectors, connectors and so forth, built for use in decimal systems, can be utilized. I

According to a feature of this invention ythe saine number select-ive operations are `'carried out not only iii accordance with the Vcharacters of the digits composing a telephone designation,

but also in accordancewith the number ofv digits. Thus a connection will be extended over one path if the called telephone designation contains four digits and over another path if the Called telephone designation contains seven digits.

According to another feature of this invention, all telephone designations contain of Vdigits though the greater percentage are called through the use of abbreviated designations of varying and much smaller numbers of digits than the actual designations. The entire system may be thus divided into a definite number of districts-geographical or otherwise, and calls established from substation to substation within a district through the use of the abbreviated designation. Calls from a substation within one district to a substation within another district, however, are established through the use of the full designation.

Though but one abbreviationof a designation has been provided for in the preferred arrangement shown in the drawings, yet it is believed to be fully within the scope and the spirit of the invention to use a second or greater number of abbreviations, whereby the districts may be subdivided and the subdivisions further divided in any manner that the conditions of traiiic make advisable.

According to another feature of the invention the total number of permutations of digits in a given number of digital positions may be used for designations. In systems heretofore devised either an extra position was provided on the dial switches and iirst selectors or allnuinhers beginning with a l Vcertain digit (constituting ten per cent. in

the decimal system) were reserved for special service such as long distance? calls.

-l`he piesent invention makes this addition to the apparatus or subtraction from General arrangement of .sg/stem.

In the general arrangement of this system each substation has a separate and distinct numerical designation. The system `then is divided into districts, and as illustrated, all designations in each district have the same first three digits.

All digits are then reversed and are listed so that it appears that all designations in each district are the same as regards the last three.

In the actual listing only the then first four digits are given as the designation-the then remaining three being given under the head of special instructions to subscribers in other districts who wish to make a foreign district or long distance call to a station in the district being considered.

In making a call the impulses sent according to the listing and, therefore, in reverse order to the actual designation of the called line, are received by a set of registers. the call `be one to a substation in the same district, then only four registers will beset and a slow acting mechanism willact to'set in operation an impulse transmitter. lf, on the other hand the call be one to a substation in another district then an additional three registers will be set in accordance with the common three digits of all substations in that district, the slow acting mechanism will fail to operate and as a consequence, the means for starting the impulse transmitter will in this case cause a switching operation to take place and extend the call over a different path. Y

rfYhe impulses, as has been said, are received and recorded by a set of registers and as soon as all are received, which is deter mined by the slow acting mechanism in the case'ot an abbreviated designation and by the full use of the apparatus in the case of the full designation, then an impulse transmittter is set in operation. In its operation, this transmitter reverses the order of the digits, so that the setting of the selector switches is in accordance with the actual numerical designations of the substations.

Thereafter the further progress of the call is the same as in any other well known step by-step system.

etcwlled description of operation.

Referring now to the drawings it will be shown how a subscriber at substation 100 may, by manipulation of his dial switch 101, establish a connection to a substation within the same district over the local trunk 102, or to a substation Within a foreign district over the local district trunk 103.

It will be assumed that the designation of the called substation within the foreign district is 1,726,385, and that the designation of the substation within the same district is 1536385. From this it will appear that the district in which this call originates is characterized in that the designation of each substation begins with the digits 153, and that `the foreign district is characterized in that the designations of the subst-ations begin with the digits 172.

According to the directories used by the subscribers in these districts it will appear, however, that each of the called substations has a designation 5836, that is, the reverse of the last four digits in each designation.

To the party originating a call in the local district the directions for calling instruct him to manipulate his dial switch in accord- 9 ance with the abbreviated designation 5836, no mention being made of the digits 351 (the reverse of 153) which characterize the local district. The directions to the same subscriber for calling 271 in the foreign district instruct him to add the digits or in other words to manipulate his dial switch to send a train of impulses representing the digits 5836271.

Accordingly, the great percentage of the traliic which terminates in the same district in which it originates is carried on through the use of the abbreviated designations whereby it appears tothe ordinary telephone user that the syst-em is of ordina-ry dimensions. Only to the class of subscribers who originate long distance calls, then, does the duty of manipulating their dial switches in accordance with the full designations devolve. In other words, the more intelligent class of people who make long distance calls or those psychologically fitted to properly remember and transmit long series ofdigits are the only ones required to do so.

It will therefore be first shown how a subscriber at substation 100 establishes a local connection through the use of the abbreviated designation 5836 and second, how the subscriber at substation 100 may establish a longv distance connection through the use of the full designation 5836271.

Removalof vthe receiver from its switchhook at the substation 100establishes a circuit for the energization of the line relay 104, extending from ground, thelet't-hand and inner left-hand armature of relay 105, Y

right-hand winding of relay 104, to battery and ground. Relay 104 attracts its arma- 1 ture and establishes a circuit for the energization of group relay 106, `from ground, innervarmature 4and contact104, winding of relay 106, to battery and giound. In turn, relay .106 attracts its armatures and energizes starterrelay 107 through a circuit eX- tending from the ground, and right-hand armature of relay 106, winding of relay 107, to battery and ground. Vhen relay 107 is energized the starter wire 108 is grounded at .its contact and armature, and a circuit for the energization of the primary magnet 110 is established in an allotted line finder switch. v

It should be noted at this point that the starter wire 108 extends to a plurality of line nder switches, oneor more of which may be allotted and ready for service. It should also be noted that a circuit extends from ground, contact and larmature of starter relay 107, side-switch wiper` 109 and its first position contact, contact and armature of primary magnet '110, Windingof primary magnet 110, winding of relay 111, to battery and ground. The current iiowing over this circuit, however, is too small to cause the energization of the primary magnet in a switch which is not as yet allotted. 1n a switch which is allotted, however, 'the relay 111 is shunted through a parallel path extending from the winding of relay 110, contact 112, wiper 113, conduct-or 114, sequence switch Contact 300 (first position), sequence switch contact 301 (first position) to battery and ground.

The primary magnet 110, through the attraction-of its armatures in this last`described circuit, breaks its own circuit and in the well-known manner st'eps the shaft carrying brushes 115, 116, 117 and 118 around until the latter makes contact with the terminal'119. established f-romground, contact and rightliand armature of relay 106, terminal 119, brush 118, rst position contact and sideswitch wiper 120, winding of escape magnet 121, winding of primary magnet 110, and thence to battery over the circuit previously described. Through the current lowing'in this circuit the escape magnet 121 is energized, the primary magnet 110 is held in the energized position, and the further rotation ot the brush shaft is prevented.'

The energization of the escape magnet 121 causes the movement of the side-switch wipers into their second positions, whereupon a circuit is established from ground,

A `circuit is thereupon the armature and contact of relay 122, second position contact and side-switch wiper 120, thence over the circuit previously described through'the windings of relay 121 and magnet 110.

Through the movement of the side-switch wiper 109, a circuit is established for the energization of the secondary magnet 123, eX- tending from ground, contact and armature of relay 107, starter wire 108, side-switch wiper 109 and its second position contact, contact and armature o1c secondary magnet 123, winding of magnet 123, to battery and ground.

Through the automatic action of the secondary magnet, brushes 115 to 117 are moved over their associated terminals until the terminals 124 to 126 are encountered. During this movement a circuit is established from grounded battery, the winding o'l`l cut-oit1 relay 105 of other line terminals similar to 124, brush 115, side-switch wiper 128 and its second position contact, winding' of marginal relay 122 to ground. The current flowing over this circuit is insuicient to cause an energization of either relay 105 or relay 122. However, the terminal 124 connected with the calling substation will 'have a potential of a different magnitude impressed upon it through the resistance coil 127 the Contact and lett-hand armature o't relay 106. contact and outer right-hand armature ot relay 104 to terminal 124, through which relay 122 will be sufficiently energized to cause it.to attract its armature. Therefore. when the brush 115 encounters terminal 124 of the calling line, the relay 122 will be energized, and the circuit for the energization of escape magnet 121 will be opened.

The denei'gization of relay 121 results in L the movement of the side-switch wipers into their third positions, whereupon relay 105 -willv be energized Yovera circuit vKtending from ground, the third position contact and side-switch wiper 128, the brush 115, the terminal 124, winding of relayv 105, to bat# tery and ground. The energization of relay 105 in the well-known manner will cause the denergization ci line relay 104, the groupV relay 106 and the starter relay 107.

The .movement of the side-switch wipers into their third positions puts the substation 100 into control ofthe registers diagrammatically shown in Fig. 2, and a circuit is established from ground` battery, the right.- hand winding oit relay 200, the normal contact and inner left-hand armature of relay 201, conductor 202, brush 129, contact 130, third position contact and side-switch wiper 131, brush 117. terminal 126 to and through the apparatus at substation 100'including dial switch 101, terminal 125, brush 116, side-switch wiper 132 and its tliird-position contact, contact 133, brush 134, conductor 903, outer lefthand armature and normal contact or' relay 01, lett-hand winding of relay 200 to ground.

Relay 200 is energized in this circuit and attracts its armature, whereby a circuit is established for the energization of the motor magnet 204. It should be noted at this point that the motor magnet 204 is the actuating means for a step-by-step sequence switch similar in construction to that shown in lUnited States lla-tent No. 1127808 oi liebruary 9, 1915 to Reynolds and Baldwin. rl`he operation of the present structure is somewhat different in that it is not under control ot a constantly rotating roller as in the patent cited but is controlled through a well known pawl and ratchet means.

The energization of magnet 204i4 causes the movements of the associated sequence switch contacts into position 2, whereupon the apparatus is in condition to receive impulses from the subscribei"s line.

According to the designation oi the called telephone the subscriber will first manipulate his dial switch 101 in accordance with the digit 5, thereby causing five rapid interruptions ot the line circuit. llpon the iirst such interruption, the relay 200 is deelnergized and in retracting its armatures establishes a circuit for the energization oi' the slow release rela-y 206, such circuit extending from ground, sequence switch 205 (posh tions 2 to 12), the contact and right-hand armature of relay 200, the winding of relay 206, to battery and ground.. 1n this circuit, this relay remains energized until after the last momentary denergization of the relay 200, when, due to the long energization thereof, its circuit will be permanently opened and it will retract its armatures, thereupon establishing a circuit for the ener-v girzation oli relay 201 extending 'from ground. sequence switch contact 205 (positions 3 to 12), contact and armature of relay 206, winding o'l relay 201, to battery and ground. Relay 201, in attracting its armatures, establishes a holding circuit for itself extending trom ground, sequence switch Contact 205 (positions 3 to 12), right-hand armature and contact of relay 201, the winding of relay 201, to battery and ground.

Upon each energization after al momentary denergization of relay 200, a circuit for the energization of motor magnet 2041 is established, as before described, and the sequence switch contacts are advanced step by step through the sending of five impulses as in the present case. The sequence switch is stepped into its seventh position, thereby closing the sequence switch contact 20.7 (position 7), the function ot which will be vliere.im.tter described.

At the end of the iirstseries of tive impulses relay 201 is energized as described, and-theconductors 202 and 203 which are up to this time extended to the windings 0i relay 200 are now switched to the windings or a similar relay 210, not shown, in a second register where the second digit of the called substation is registered.

ln a similar manner the third digit of the designation is registered on a Vthird register and after the operation ot the slow release relay therein the lines leading to the substation are switched to the windings of relay 210. The subsequent action of the fourth register under control of relay 210 is in every respect similar to that described in connection with the first register except that due to the receipt or six impulses it will be set in position 8, and sequence switch contact 212 (position 8), will be closed for a purpose to be hereaiter described.

Thereafter, the conductors 202 and 203 are switched from association with relay 210 into association with relay 220 through the contacts of relay 221. in a manner similar to that described, relay 220 attracts its armatures, causes the euergiz/.ation of motor magnet 22st and thereby causes the movement of the associated sequence switch contact into position 2.

A circuit is now established from ground, sequence switch contact 222 (position 2), winding of relay 221 to battery and ground. Relay 221 is a slow-acting mechanism, being illustrated in this case as a dash pot type of relay. The energization of such a relay results in the attraction of its armatures only atter a deiinite period of time has elapsed, which period of time may be adjusted to meet any requirement.

Vlntne present case, this relay isv so adjusted that it will not energize until a sut licient time has elapsed tov indicate that no more impulses will be transmitted over the circuit leading from the substation. W hen said period oi time has elapsed therefore, the relay attracts its armatures and transfers the circuit leading from the substation from control relay 220 to control relay 302. The circuit for the energization oit relay 302 may be traced irom ground, battery, wimling` ot' relay 302, sequence switch contact 303 (position 1), conductor 3011, alternate contact and inner armature oli relay 221, alternate contact and outer letthand armature of relay 211, alternate contact and outer leitdrand armature ori, relay 201, conductor 203, thence over the circuit previously traced to conductor 202, inner lett-hand arrmrture and alternate Contact ot' relay 201. inner letthand armature and alternate contact et relay 211 outer right-hand armature and alternate contact of relay 221, conductor 305, sequence switch contact 306 (position 1), left-hand winding of relay 302 to ground.

Relay 302 is energized in this circuit and thereupon establishes a circuit Vfor the energization of motor magnet 307, extending soA from ground, contact and armature of relay 302, winding of motor magnet 307 to battery and ground. Motor magnet 307 Vcontrols a sequence switch similarto those used as registers heretofore describedl and upon its present energization drives its associated contacts into their second positions. Thereupon, the impulse transmitter is caused to operate. p

In position 2 of the sequence switch,'under control of the motor magnet 307 a circuit is established for the energization of relay 111 and the consequent seizure of the local trunk 102. This circuit extends from ground, sequence switch contact 308 (position 2), conductor 114, wiper 113, contact 112, winding of relay 111 to'battery and ground.- Relay 111 thereupon attracts its armatures and establishes a locking circuit for itself fromits winding, its contact .and inner lower armature over the side-switch wiper 128 and its third Vposition contact to ground.

Thereupon, the selector switchwhich may be of any well-known type, connected to the local trunk 102 is seized through a path of low resistance being bridged from terminal 135 to 136 as follows: from terminal 135, alternate contactand upper armature of relay 111, contact 139, brush 140, conductor 141, sequence switch contact 309 (positions 2 to 11), sequence switch contact 309 (position 2), sequence switch contact 310 (position 2), sequence switch contact 310 (positions 2 to 11), conductor 142, brush 143, contact 144, inner upper armature and alternate Contact of relay 111, to terminal 136.

In position 2 of the sequence switch controlled by motor magnet 307, a` circuit is established from ground, interrupter 311, sequence switch contact 312, (position 2), the winding of motor magnet 307 to battery and ground. VVMotor magnet 307 is energized and by moving its contact into the third position, opens the circuit just traced. Thereupon, a circuit will be established from ground, sequence switch contact'313 '(position 3), contact and right-hand armature of relay 314 to battery and ground. v

lt should be noted at this point that the conductors 141 and 142 which extend to the selector switch on the local trunk 102 are connected through sequence switch contacts 309 and 310 respectively, to the contact and lefthand armature of relay 314 through which a bridge of low resistance is put on such selector switch until the relay 314 is energized. y p The circuit just described for the energization of relay 314 causes it to attract its armatures and at the same timeimove the wiper 315 step by step over its associated contacts. Each time that it moves its armature, the bridgeof low resistance upon the local Vtrunk is momentarily opened in a manner similar to the action caused by the subscrlbers dial switch, whereby the selector is actuated.

' It will be noted that sequence switch contrunk has therefore been driven to its sixth selective position, a circuit will be established from the ground on contact 318 to brush 315, the commutator segment 319 in association with the brush 315, thewinding of relay 320 to battery and ground. Relay 320 short-circuits the contact and left-hand armature of relay 314 through its contact and left-hand armature and at the same. time establishes a holding circuit for itself which is maintained until `the brush 315 has again reached normal position. Such circuit may be traced from ground, the contact and righthand armature 320, the brush 315, commutator segment 319, the winding of relay 320 to battery and ground.

As the brush 315 encounters the grounded 9 contact 318, a circuit is established from such ground, the brush 315, the commutator segment 319, sequence switch contact 312 (positions 3 to 10) the winding of motor magnet 307 to battery and ground. The motor magnet is energized in this circuit and the sequence switch contacts are moved to their fourth positions, but the motor magnet is not dnergized until the brush 315 is disconnected from the commutator segment 319 at its normal position. The circuit for the energization of relay 314 is maintained over a circuit from ground, lcontact and righthand armature of relay 320, sequence switch contact 313 (position 4) and thence over the circuit previously traced.

Whenv the brush 315 reaches its normal position relay 320 is denergized and in'turn relay 314 is denergized so that the brush is halted until the sequence switch is moved into a new position.

Upon the denergization lof relay 320, motor magnet 307 is momentarily denergized, whereupon a new energizing circuit is established from ground, interrupter 311, sequence switch contact 312 (position 4), winding of motor magnet 307 to battery and ground and the sequence switch contacts are driven into their fifth positions.

In the fifth position a ground is extended to the register contacts of the third register throughv sequence switch Contact 316 (position 5), and conductor 321, whereby the contact 322 is grounded, thel brush 315 takes three steps, the circuit leading to the local ond selector switch thereon is driven to its third selecting position in a manner similar to that described in connection with the fourth register.

Thereafter, the sequence switch under control of the motor magnet 307 passes through itspositions successively andthe impulse transmitter causes the actuation of the selector and connector switches over the local trunk 102 until the connectorl switch is driven into association with the terminals of the desired line, at which time the sequence switch under control of motor magnet 307 is left in the eleventh position and a circuit is established from ground, batter", sequence switch contact 301 (position 11), conductor 323, contact and left-hand armature of relay 145, wiper 146, contact 147, third position contact and side switch wiper 120, winding of escape magnet 121, winding of primary magnet 110, contact and inner lower armature of relay 111, side-switch wiper 128 and its third position contact to ground The energization of the escape magnet 121 causes the movement of the side-switch wipers into their fourth positions, whereupon, the .circuit from the substation is directly connected to the local trunk 102 through the side-switch wipers 131 and 132y in their fourth positions.

1 ln the fourth position a circuit is established from ground, the fourth position contact and side-switch wiper 148, contact 147, wiper 146, winding` of relay to battery and ground.

It should be noted at this point that relay 145 is of such resistance that it will neither be energized or cause suliicient curreiit to ilow to energize the relays 121 or 110 through which the circuit is formed in the third positions of the side-switch wipers.

yllllhen a direct ground, however, is placed on its winding as in the present ease, it is energized, and upon attracting its armatures it establishes a circuit from ground, the contact and right-hand armatiufe of relay 145, the contact and armature of magnet 149, the winding thereof to battery and ground. Magnet 149 causes the brushes 146, 113,129, 140, 134 and 143 to be stepped around over their associated contacts until the contact 147, free of ground and which therefore denotes an idle line {inde-r switch is encountered, whereupon, the relay 145 deenergizes and by opening the circuit of rclay 149 causes the brushes to rest in association with contacts leading to such idle line finder switch.

In position 11 of the sequence switch under control of motor magnet 307 a circuit is-established from ground, interruptor 311, sequence switch contact 312 (position 11). windingl of'm'o'tor magnet 307 to battery and ground. Motor Inaglnet 307 is energized in Vtact 235 (position 1), conductor this circuit, whereupon the associated sequence switch contacts are driven into position 12. Y

ln position 12, a circuit is established from ground, interruptor 324, sequence switch Contact 325 (position 12), conductor 326, and thence through sequence switch lcontacts 215 and 203 and through similar sequence switch contacts to the windings of the associated motor magnets.` Such quence switch contacts being in Veach case closed in their positions 3 to 13 inclusive. TJnder the influence of the interruptor 324 each one of the sequence switches used as registers will he returned step by step to their first positions, and when the last one reaches itsiirst position a circuit is octallished from ground, sequence switch voir tact 209 (position 1), sequence switch con-- tact 216, (position 1), sequence switch i tact 225, (position 1), sequence swiLh quence switch contact 312 (position winding of motor magnet 30'? to batt l, and ground. Motor magnet 307' is energized in this circuit and moves its associated contacts into the thirteenth position, whereupon they are returned to their normal or first position through the iniluence 4of the interrupter 311 and the sequence switch contact 312 (positions 13 to 18 inclusive). Y

lt will be noted that the of iin pulses representing the digits 5836 as regis tered were transmitted to the selecto-r switches on the local trunk 102 in the reverse order, thatis as 6335, which is the abH breviated numerical designation of the called line. The digits 153 which characterize this group were not transmitted or in other words were automatically taken caro of in the arrangement of the s stein.

1t will now be shown how the addition o l: i

cause the substation having the same curtailed designation as the called substation just described but in a group characterized by the digits 172 to be ci lied.

The description of the' registering of the digits 5836 in this caso will be similar in every .respect` to that previously given. llhen, however, the circuit for the one tion of the relay 221 is established, a i cncerin action will occur.l ln the present case a series of two short impulses will be transmitted from the substition 100 before the relay 221 can attract its armatures. These two short impulses will cause the actuation of relay 220 and in turn the motor magnet 224 in such la manner that toe sequence switch under control of motor niagnet 224 will be driven into its fourth position and the contact (position si) will be closed. As the sequence switch mores out of position 2 the energizing circuit for the relay 221 will be opened. At therend of this series of impulses, the slow acting relay 226 will become denergized and in turn the Y relay 227 will be energized, whereupon the circuit leading over conductors 202 and203 to the substation wiil be switched to a sixth register.

In ra manner similar to that described the sixth register will be moved to its ninth position, thereby registering the digit 7.

At the Acompletion of this registration the relay 230 will become energized and 1n a Vmanner similar to that described, the seture of relay 237, alternate contact and outer left-hand armature of relay 227, vnormal contact and innerright-hand armature ot relay 221, alternate contact and outer lefthand armature of relay 211, alternate contact and outer left-hand armature of relay 201,` conductor 203, brush 134, contact 133, third position contact and side-switch wiger 132, brush 11G, terminal 125, to and through the apparatus of the substation 100, terminal 126, brush 117, side-switch wiper 131 and its third position contact, contact 130. brush 129, conductor`202, inner lett-hand armature alternate contact of relay 201, inner left-hand armature and alternato contact of relay 211, outer right-hand armature and normal Contact of relay 221.. inner left-hand armature and alternate contact olV relay227, inner left-hand armature and alternate contact of relay 23 g sequence switch Acontact (position 1). left-hand windinn of relay 350 is energized. Y i

Thereupon, a circuit is established 'from ground, Vcontact and armature ot relay 350. winding' of motor magnet 353 to battery and ground, whereupon the sequence switch batteryv and ground, relay 350 Y under control. of this motor magnet is morcd to its second position. UnderV control ot sequence switch contacts 359 and 360 a path ollow resistance is placed between the terminals 150 and 151 of the long distance trunk 103. This circuit'may be traced from termi- -nal 150, normal contact and upper outer armature ot relay 111. contact 139, brush 140 conductor 141, sequence switch Contact (positions 2 to 17), sequence switch Contact 359 (position 2), sequence switch contact 360 (position 2), sequence switch contact 360 (positions 2 to 17), conductor 142, brush 143, contact 144, inner upper armatureand normal contact of relay 111, to terminal 151.

ln position 2 ot the sequence switch under control et motor magnet 353, a circuit is cstablished t'rom ground, interrupter 311, sequence switch contact 354 (position 2), winding ot motor magnet 353 ground, whereby the sequence switch is moved to its third position. ln the third position a circuit is established from ground, sequence switch contact355 (position 3), contact and right-hand armature of relay 314, winding of relay 314 to battery and ground.

The subsequent action of the sequence switch under control of motor magnet 353 and the impulsetransmitter is similar to that previously described. Through the sequence switch contacts 356 and 357, the registers startin r with the seventh are grounded in turn, the brush 315 is caused to travel overiits contacts, the magnet 314 is caused to interrupt a line circuit over conductors 141- and142 in accordance with the registereddigits until the digit 5 which was the first to be registered is retransmitted over the long` distance trunk 103 to the connector switch thereof. y

As the brush 315 reaches its normal position. att-er tive interruptions of the line circuit have been caused in response to the setting otthe lirst register, the sequence switch under control of motor magnet 353 will be moved to the seventeenth position, whereupon a circuit will be established from 'ground battery.I sequence switch contact quence switch contact 358 (position 17),`to

ground. Through this circuit the escape magnet 121 will be energized and the sideswitch wipers will thereupon be moved into their fourth positions where the calling substation 100 will be directly extended to the long distance trunk 103.

In the fourth' position ofthe line linder sine-switch wipers a .ircuit is established from ground. fourth position contact and. side switch wiper 143,` contact 147, brush 146` winding ci relay 145. to batteryrand ground. Relay145 attracts its armatures and estalilishes a circuitheretofore described for the energization of stepping magnet 149. Thereafter the action of the allotter switch is the same as before and the action of the registers and. impulse transmitter in their return to normal is the same.Y

At the conclusion ot 'the conversation held either over the long distance trunk 103 or to battery and the local trunk 102, the connection is restored in the usual manner. This may be accomplished by placing a ground on the third or test conductor, which, upon being transmitted. through the outer lower armature of relay 111 through the armature and contact of relay 15a, the off-normal contact 155, the Winding ot' release magnet 156 to battery and ground, will cause the line finder switch to be restored to its normal condition.

W hat is claimed is:

1. ln a telephone exchange system, lines arranged in numerical order accessible to calling li'nes by composite paths comprising a plurality of simple paths, selective switches arranged to select a composite path by means of successive selections of simple paths, the number of selections being greater than the number of characters in the designation of the line to which such path is to be extended.

2. In a telephone exchange system, lines arranged in numerical order divided into groups and accessible to calling lines ot all but the same group by composite paths comprising a plurality of simple paths, the number of which is greater than the number of characters in the full designation of the line to which such path is to be extended and aecessible to calling lines et the same group by composite paths comprising a plurality of simple paths, the number ot which is greater than the number of characters in the abbreviated designation of the line to which such path is to be extended and less than the number of characters inthe full designation ot the line to which such path is to be extended.

3. ln a telephone exchange system, lines arranged in .numerical order, a calling device associated with each of said lines, registers responsive to said calling devices. impulse transmitters responsive to said registers, selective switches for interconnecting said lines Vresponsive to said impulse transmitters.l said impulse transmitters being arranged to transmit series of impulses in the reverse order to which they are registered. ln a telephone exchange system, lines arranged in numerical order and divided into groups, a full and a curtailed designation for each of said lines, means responsive to the transmissi-'in ot impulses representing the full design` m .ior extending a c ling line in one group over a trunll leading to a secondV group, und means rcsponsiye to the transmission et impulses reprcscnting` the curtailed designation tor extending a calling line in said second group overa trunk leading to the same group.

ln telephone exchange system, lines arranged in numerical order, designation vfor eac-hef said lines, selective switches for interconnecting said lines, means for setting said switches in accordance with the digits of said designations, and means forV making an additional selection in accordance with the number oi' digits in said designation.

6. In a telephone exchange system, lines arranged in numerical ord-cr, selective switches for interconnecting said lines, a designation for Veach of said lines comprising a plurality ot digits, and means ter setting said switches on the terminals of a called line through the use of less than the iull number of digits comprising the designation of that line.

7. ln a telephone exchange system, lines arranged in numerical order each provided 'ith a designation listed in the reverse order, subscriber controlled means for registering such reversed designations, selective switches 1for interconnecting said lines, means responsive to said registering means ttor setting said selective switches, and means for causing such sett-ing to talre place in the reverse order to that in which said registers were set.

8. ln a telephone exchange system, an e2;- change district, lines arranged in numerical order Within said district, a iull number ot designations :for such lines comprising a given number of characters in all posible permutations, selective switches Jfor interconnecting said lines responsive to series oi impulses Vrepresenting such designations, said switches being arranged to a capacity equal to Ithe said full number oi? designations, foreign districts, a series ot longer des' nations for use in calling lines in said :foreign districts, and means responsive to series of impulses representing such longer designations for extending said lines to said 'foreign districts.

9. ln a telephone exchange system, lines arranged in numerical order and divided into groups, selector switches for interconnecting said lines arranged in order for successive actuation, a designation for each oi said lines comprising a full number of characters for use in intergroup calling, means for actuating said selector switches starting With the first in order, an abbreriated desigl tion for each of said lines coinprising than the full number oi the same characters for use in intragroup alling. and means for actuating said selector switches starting 1with a later one than the iirst in order.

10. ln a telephone system, telephone lines, and means tor interconnecting said lines comprising means-for selecting a line rcsponsive to the number of char( eters in the designation ot a called line and other means Vfor selecting lin responsive to the characters in the designation oit a called line.

11. ln a telephone system, telephone lines and means 'for interconnecting `said lines comprising means for making a primary selection of lines in the direction of the called line responsive to the number of characters in the designation of the called line, and selective switches for making the final selection of lines in the direction of the called line responsive to the characters in the designation of the called line.

12. In a telephone system, telephone lines,

10 said telephone lines being identified for purposes of calling by designations containing varying numbers of characters, machine switching means for interconnecting said lines, and means responsive to the number of characters n the designation of a called line for selecting a trunk to a train of selective switches of a corresponding number. In Witness whereof, I hereunto subscribe my name this 20th day of July, A. D. 1917.

JOHN A. HALL. 

